The Professional Responsibility course (by whatever name it is called at your school) is about the law and ethics that govern relationships lawyers have with clients, other lawyers, the profession, the justice system, and the public. It is the only law course in the typical law school curriculum that is about what lawyers do. In Torts, Contracts, and so on, you study law that affects clients' relationships with others and that lawyers interact with as an expert a step removed from the actual effect of the law. In Professional Responsibility, by contrast, the law you study is directly about the lawyer's relationships and your future role.